As is in heavy fermion systems, the \(t\) -\(J\) -\(K\)  model contains two competing
energy scales that support different ground states. The Heisenberg
superexchange \(J\)  favors an antiferromagnetic long-range order, while the
Kondo coupling \(K\)  tends to screen the local spins and form a nonmagnetic
ground state. In nickelates, due to the large charge transfer energy between
O-\(2p\)  and Ni-\(3d_{x^{2}-y^{2}}\)  orbitals, \(J\)  is expected to be smaller
that that (about 100 meV) in cuprates. Raman scattering measurements
confirmed this expectation and estimated \(J\approx 25\,\) meV in bulk NdNiO\(_2\) 
[1]}. First-principles calculations also suggested \(J\)  of the order
of 10 meV [2]}. There is at present no direct measurement of
the Kondo interaction \(K\) . However, from the observed resistivity minimum at
70-100 K in NdNiO\(_2\)  and LaNiO\(_2\)  [3]}, [4]}, \(K\)  may be
roughly estimated to be of the order of a few hundred meV [5]}, [6]}, [2]}. Thus for undoped nickelates, the Kondo
coupling is a relatively large energy scale.
